This invention relates generally to the field of drilling rig management systems, and more particularly to an automated method and system for recognizing well control events.
Drilling rigs are typically rotary-type rigs that use a sharp bit to drill through the earth. At the surface, a rotary drilling rig includes a complex system of cables, engines, support mechanisms, tanks, lubricating devices, and pulleys to control the position and rotation of the bit below the surface.
Underneath the surface, the bit is attached to a long drill pipe that carries drilling fluid to the bit. The drilling fluid lubricates and cools the bit, as well as removes cuttings and debris from the well bore. In addition, the drilling fluid provides a hydrostatic head of pressure that prevents the collapse of the well bore until it can be cased and that prevents formation fluids from entering the well bore, which can lead to gas kicks and other dangerous situations.
Automated management of drilling rig operations is problematic because parameters may change quickly and because down hole behavior of drilling elements and down hole conditions may not be directly observable. As a result, many management systems fail to accurately recognize the presence and/or absence of important drilling events, which may lead to false alarms and unnecessary down time.
The present invention provides an automated method and system for recognizing well control events that substantially reduce or eliminate the disadvantages and problems associated with previous systems and methods. In a particular embodiment, the flow of fluids into or out of a formation during well operations is determined based on sensed data and the state of well operations. Accordingly, influx or outflux of fluids in a well may be accurately recognized during drilling, tripping and other suitable well operations.
An automated method and system for recognizing a well control event includes determining a state of drilling operations. When drilling operations are in a circulating state, a benchmark for a relative flow value is determined. The relative flow value may be based on a flow of drilling fluid into a well bore and a flow of drilling fluid out of the well bore. A limit on variation of the relative flow value is determined from the benchmark. A cumulative sum for the relative flow value is determined over time in response to the relative flow value exceeding the limit. A well control event is recognized based on the cumulative sum.
In a particular embodiment, the present invention accurately recognizes inflow and outflow well control events based on drilling system parameters and dynamically determined limits. Inflow and outflow events may be recognized during drilling and/or circulation states of drilling operation as well as during non-circulation states such as constant bit position, tripping-out and tripping-in. In addition, for drilling ships, semi-submersibles, and other buoyant drilling vessels and structures, heave may be determined and compensated for in recognizing events.
Technical advantages of the present invention include providing an automated method and system for recognizing well control events. In a particular embodiment, well events are recognized based on the state of well operations. As a result, well events may be accurately recognized during drilling, tripping and other suitable well operations. In addition, the state determination engine provides a modular architecture to event recognition. Accordingly, a control system for a well may be readily adapted to recognize events during different stages of the well.
Still another technical advantage of the present invention includes providing an improved drilling rig. In particular, sensed and/or reported data is utilized to enhance accuracy and to allow for earlier, more effective and more efficient recognition of potentially hazardous events such as well control events, stuck pipe, and pack off. This may result in the more effective taking of corrective operations and a reduction in the frequency and severity of undesirable events.
Still another technical advantage of the present invention includes providing heave compensation for buoyant drilling vessels and structures. In particular embodiments, circulation rates into and out of the well bore as well as mud tank volumes used in determining events may be adjusted for changes caused by heave or other displacement of the drilling platform.
It will be understood that the various embodiments of the present invention may include some, all, or none of the enumerated technical advantages. In addition, other technical advantages of the present invention may be readily apparent from the following figures, description and claims.